The present invention relates to an automotive anti-lock brake control system, and more particularly to an improved automotive anti-lock brake control system in which valve portions of electromagnetic valves for controlling brake hydraulic pressures of wheel brakes and hydraulic pumps are accommodated in a housing. Further, solenoid portions which constitute the electromagnetic valves in cooperation with the valve portions protrude from one side of the housing, and an electric motor for driving the hydraulic pumps is joined to another side of the housing. Moreover, an electronic control unit for controlling the energizing of the electric motor and the solenoid portions and a cover for covering the solenoid portions are joined to the one side of the housing, and a coupler is provided on the cover for connection with an external electric circuit.
Conventionally, a control system of this type is known in, for example, Japanese Patent Unexamined Publication No. Hei.8-11691.
Incidentally, noise attributed to electromagnetic waves occurred from an electric motor of an anti-lock brake system may be generated from the on-board radio while the anti-lock brake control system is in operation. In order to prevent the generation of such noise, it is known as a well-accepted technology to connect in parallel an electric component such as a capacitor for countermeasure against noise to the electric motor.
Referring to FIG. 9, a conventional technology will be described in which an electric component is used as a countermeasure against noise. A positive side conductive line 46 having a relay circuit 45 interposed at an intermediate position along the length thereof is provided on a substrate 17 of an electronic unit 16. The positive side conductive line 46 connecting a motor coupler terminal 37P that is to be connected to a positive terminal of a battery 48 with a positive terminal 39P of an electric motor 12. A motor coupler terminal 37N that is to be connected to a negative terminal of the battery 48 is connected to a negative terminal 39N of the electric motor 12 without passing through the substrate 17. A pair of substrate coupler terminals 38P, 38N is connected to the substrate 17. The terminals 38P, 38N are connected to positive and negative terminals of the battery 48, respectively, and independent from the respective coupler terminals 37P, 37N. Moreover, an electric component such as a capacitor for countermeasure against noise is mounted on the substrate 17 so as to be interposed between the conductive line 46 and the substrate coupler terminal 38N that is connected to the negative side of the battery 48.
However, a power supply line on the electric motor 12 including the positive side conductive line 46 is formed by a conductor having a large cross-sectional area. On the other hand, a power supply line for the substrate 17 is formed by a conductor having a cross-sectional area which is made relatively small. Accordingly, if there occurs a disconnection along the line connecting the substrate coupler terminal 38N and the substrate 17, the relay circuit 45 becomes unstable, resulting in the possibility that the electric motor 12 is activated unintentionally.
The present invention was made in view of the situation, and an object thereof is to provide an automotive anti-lock brake control system which prevents the generation of noise attributed to the electric motor and avoids allowing only the substrate side of the electric control unit to be put in a non-grounded condition so that an undesired activation of the electric motor is prevented.
The above-mentioned object can also be achieved by an automotive anti-lock brake control system, according to the present invention, comprising:
electromagnetic valves 5A to 5D, 6A to 6D, having valve portions 5a, 6a and solenoid portions 5b, 6b for controlling brake hydraulic pressures of wheel brakes BA to BD, respectively;
hydraulic pumps 11A, 11B for generating the brake hydraulic pressures;
a housing 20 accommodating the valve portions 5a, 6a of the electromagnetic valves and the hydraulic pumps 11A, 11B, wherein the solenoid portions 5b, 6b of the electromagnetic valves 5A to 5D, 6A to 6D protrude from one side 21a of the housing,
an electric motor 12 joined to another side 20b of the housing 20 for driving the hydraulic pumps 11A, 11B;
an electronic control unit 16 for controlling the energizing of the electric motor 12 and the solenoid portions 5b, 6b; 
a cover 21 joined to the one side 20a of the housing for covering the solenoid portions 5b, 6b and the electronic control unit 16;
a coupler 35 provided on the cover 21 for connection with an external electric circuit, the coupler 35 having positive and negative motor coupler terminals 37P, 37N which are connected to ends of an external power source 48 respectively;
a substrate 17 provided in the electronic control unit 16;
a positive side conductive line 46 having one end connected to a positive terminal 39P of the electric motor 12 and the other end connected to the positive motor coupler terminal 37P, the positive side conductive line 46 having a relay circuit 45 interposed at a position along the length thereof, and the positive side conductive line 46 provided on the substrate 17;
a negative side conductive line 47 having one end connected to a negative terminal 39N of the electric motor 12 and the other end connected to the negative motor coupler terminal 37N, the negative side conductive line 47 provided on the substrate 17 so as to function as a negative side power supply line for the substrate 17; and
an electric component 50 mounted on the substrate 17 for preventing a generation of noise attributed to the electric motor 12, the electric component 50 connecting the positive side conductive line 46 to the negative side conductive lines 47.
In the above-mentioned automotive anti-lock brake control system according to the present invention, the electric component may be a capacitor 50.
In addition, in the above-mentioned automotive anti-lock brake control system according to the present invention, the external power source may be a battery 48.
According to the construction described above, since the electric component acting as the countermeasure against noise is connected to the electric motor in parallel, noise attributed to electromagnetic waves generated from the electric motor is prevented from being generated in on-board equipment such as a radio. Moreover, since the positive side and negative side conductive lines which continue to the positive and negative terminals of the electric motor, respectively, are provided on the substrate of the electric control unit with the negative side conductive line being used as the substrate negative side power supply line, there occurs no status in which only the substrate side is put in a non-grounded condition to thereby avoid allowing the relay circuit on the substrate to become unstable, whereby the possibility can be eliminated that the electric motor is activated unintentionally.